1.1.1 Energy Stores & Transfers

• Energy stores

  • Thermal Energy Store
  • Kinetic Energy Store
  • Gravitational Potential Energy Store
  • Elastic Potential Energy Store
  • Chemical Energy Store
  • Magnetic Energy Store
  • Electrostatic Energy Store
  • Nuclear Energy Store
• Thermal Energy Store

  Energy stored in a system due to its temperature
• Kinetic Energy Store


  Energy stored in a moving object
• Gravitational Potential Energy Store

  Energy stored in an object due to its position in a gravitational field
• Elastic Potential Energy Store


  Energy stored when an object is stretched or compressed
• Chemical Energy Store

  Energy stored in chemical bonds
• Magnetic Energy Store


  Energy stored in magnetic fields
• Electrostatic Energy Store


  Energy stored when charges are separated
• Nuclear Energy Store

  Energy stored in the nucleus of atoms
• Energy transfer processes

  • Mechanically
  • Electrically
  • By Heating
  • By Radiation
• Mechanically


  Energy is transferred when a force is applied to move an object
• Electrically


  Energy is transferred when electric charges move through a circuit
• By Heating


  Energy is transferred from a hotter object to a cooler one
• By Radiation


  Energy is transferred by waves such as light or sound
• Energy cannot be created or destroyed, only transferred or transformed from one form to another
• The total energy in a closed system remains constant
• Energy transfers

  • A Pendulum
  • A Bouncing Ball
  • A Roller Coaster
• A Pendulum

  Energy is transferred between gravitational potential energy store and kinetic energy store
• A Bouncing Ball

  Gravitational potential energy is transferred to kinetic energy as it falls
• A Roller Coaster

  At the top, it has maximum gravitational potential energy, which is transferred into kinetic energy as it descends
• Energy Transfer Diagrams


  Sankey diagrams show how much energy is transferred to useful stores and how much is wasted
• Efficiency

  The ratio of useful energy output to total energy input, expressed as a percentage
• Efficiency calculation

  Efficiency = (Useful energy output / Total energy input) × 100%